1. FIELD
The subject invention is in the field of conveyors, specifically conveyors for use with bulk materials such as fertilizer, sawdust and grains and generally known as particulate materials. More specifically, it is in the field of particulate material conveyors usable on conveyances such as trucks and trailers and, still more specifically, such conveyors in which the material is supported on a floor comprised of longitudinal members called slats and the material is moved by longitudinal oscillation of groups of slats.
2. PRIOR ART
The U.S. patents listed below are a selection of prior art in this still more specific field.
4,679,686 7/1987 Foster 5,088,595 2/1992 Hallstrom, Jr. 4,749,075 6/1988 Foster 5,238,360 8/1993 Foster 4,785,929 11/1988 Foster 5,267,641 12/1993 Hallstrom, Jr. 4,856,645 8/1989 Hallstrom, 5,323,894 6/1994 Quaeck Jr. 4,858,748 8/1989 Foster 5,325,957 7/1994 Wilkens 4,896,761 1/1990 Foster 5,335,778 8/1994 Wilkens 4,940,132 7/1990 Foster 5,346,056 9/1994 Quaeck 4,984,679 1/1991 Foster 5,560,472 10/1996 Gist 5,064,052 11/1991 Foster
The prior art conveyors suffer from wear and failure because they are relatively complex and incorporate various kinds of seals to prevent particulate material from migrating through the floor between the slats. The wear, failure and complexity all add to the costs of using these conveyors. For example, the Foster '686, '075 and '929 conveyors all use pluralities of bearings to support the slats, as many as 1300 in an average trailer installation. Installation of these bearings is done by hand and requires considerable man-hours. For another example, the seal strips used between slats in the conveyors of Foster '132, '679 and '052 are known to require replacement which is costly because of the repair costs and the downtime required for the repairs. Such seals also introduce an extra component of friction into the operation of the conveyors, further adding to the cost of operation.
In Hallstrom, Jr., '645 and '595, there are no seals between the edges of the slats and particles collect in channels below the slats. Seals are used to prevent these particles from migrating into the bearings supporting the slats. The accumulation of these particles can be troublesome.
Quaeck (the inventor of the subject invention), in his patents '894 and '056, shows reciprocating conveyors with no seals between the slats and having a liquid tight base structure. Particles which fall between the slats accumulate in grooves, do no harm and can be flushed out during cleaning of the conveyor. The expense of a liquid tight base is rarely justifiable. Also, in Quaeck '894 the beams on which the bearing strips and slats of the reciprocating floor are extrusions with each extrusion comprising multiple beams or beam parts. This construction involves so-called "dead weight" of material between the beams and beam parts. This extra weight increases the costs of manufacturing and using the floor.
In the "walking floors" of Gist '472, the slats have flanges at each of their edges and the flanges serve as both bearings and seals, called bearing/seals. This construction requires use of a guide rail for each slat, with associated fasteners and results in relatively low bearing areas. Since some particulate matter is abrasive, the flanges and/or bearing material tend to wear and the wear tends to be uneven, further decreasing effective bearing area and sealing capability. The flanges (called ears in Gist) are more likely to wear than the high molecular weight bearing material and repair might require replacement of the slats having worn flanges.
In view of the prior art, the primary objective of the subject invention is to provide a reciprocating conveyor which has no seals but is impervious to particulate matter. A second important objective is that the conveyor be mechanically and structurally simple compared to related prior art. Related objectives are that (1) the floor be simple to install with all fastening done from above floor level and (2) the number of components (parts count) be relatively low. Another objective is that the structure involve a minimum of dead weight.